1. Field of the Invention
The present invention relates generally to a color picture tube of a monitor. In particular, the present invention relates to a degaussing circuit for a color picture tube (CPT) which can automatically degauss the CPT when a power conservation mode of the monitor is released.
2. Description of the Prior Art
Generally, in a CPT, electron beams which have been emitted from a cathode heated by a heater are controlled, accelerated, focused, and then strike phosphor dots on a fluorescent screen of the CPT to display a video signal. During these processes, electromagnetic waves are produced from the CPT, and exert harmful influence upon the peripheral circuits of the CPT and the human body. Accordingly, in order to eliminate such electromagnetic waves, the CPT is provided with a degaussing device for degaussing the electromagnetic field which is instantaneously produced especially when the power is initially supplied.
According to a conventional degaussing device, if a power switch is turned on and an initial power is supplied to the CPT, the degaussing device operates for a predetermined time to degauss the electromagnetic waves produced from the CPT. As a result, the degaussing device performs the degaussing operation only when the power in initially supplied, and then will not perform the degaussing operation until the initial power is supplied again after the power is off.
Recently, most video display appliances such as monitors employ a power conservation function for preventing unnecessary power consumption of the appliance. Thus, during a normal operation of the appliance wherein a power conservation mode is released, the degaussing operation is not performed without actuating a separate degaussing switch. If such a degaussing switch is not provided on the appliance, the electromagnetic waves produced from the CPT cannot be eliminated at all during normal operation of the CPT.